In the OTFS literature, the delay domain is usually subdivided into two parts: indices \(n\)  for which \(nT\)  is smaller than the delay \(\tau _p\) , and indices greater than or equal to the delay \(\tau _p\) , see for instance [1]} or [2]}. For indices \(n\)  with the property \(nT < \tau _p\) , an additional complex factor is introduced. However, considering OTFS by means of the DZT, we immediately recognize this complex factor given due to the quasi-periodicity of the DZT.
